Boris is teaching a math course to 180 incoming students. He is interested in comparing his effectiveness teaching this course using activity-based learning to his effectiveness teaching this course using textbook presentation. He gives each of his students a pretest and forms two groups of 90 students each. To help make sure that the groups are similar in composition with respect to factors such as age, math ability, and test anxiety, the students are randomly assigned into the two groups. One of the two groups is randomly assigned to be taught by Boris using the activity-based learning approach for the duration of the course, and the other group will be taught by Boris using textbook presentation for the duration of the course. At the end of the course, Boris will test all of the students again with a posttest, and he will examine the increase in test score from the pretest to the posttest for each group. (a) First choose whether the procedure described above is an observational study or a designed experiment. Then further categorize the procedure by choosing the correct type of observational study or designed experiment. O Observational study prospective O retrospective O Designed experiment O double-blind O completely randomized (b) Which one of the following best describes the explanatory (independent) and response (dependent) variables? O The explanatory variable is the teaching approach and the response variable is the math ability. O The explanatory variable is the math ability and the response variable is the increase in test score. O The explanatory variable is the increase in test score and the response variable is the teaching approach. O The explanatory variable is the teaching approach and the response variable is the increase in test score. (c) Suppose there is a significant difference in the test score increases between the activity-based learning approach and the textbook presentation approach. Has Boris found evidence to support a claim that the difference in the test score increases is caused by the choice of teaching approach? Choose the best answer below. O Yes. It's possible as long as the procedure was well-designed and all other variables that might influence the result were controlled for. O No. Because Boris knows the teaching approach each student was taught with, it is not possible to find evidence to support any claim about a relationship between the test score increase and the teaching approach. O No. There is no procedure, however well-designed, that can give evidence to support a claim of a cause-and-effect relationship. X 3